Thank you for posting in Intel community forum, hope this message find you well and apologies for the delayed in response.
Unfortunately per my understanding the Intel UPDS program are limited to debug, compile and run the program for NIOS II processor.
There are minor changes allowed in the register content (part of debugging purposes), however for editing codes, would recommend to go for external editor.
Please do let us know if that clarify your question.
Note: as references here is the tutorial user guide for the monitoring program.
Thanks for your help, I haven't question about this topic now, you can close it.
By the way, mabe you can help look at another topic? https://community.intel.com/t5/Intel-FPGA-University-Program/About-the-Using-the-Pre-loader-Software-for-the-A9-Processor/m-p/1253425#M4053
Hope this message find you well and good to know that it clarify your doubts, we would be closing the thread. If you have further queries, Please do post a response in the next 15 days.
After 15 days, this thread will be transitioned to community support. The community users will be able to help you with your follow-up questions.
For the other topic mention, colleague of mine which is the expert in the area will be guiding you through.